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Corn silage is one of the unique feeds in our livestock diets. It is universally grown in almost all of our dairy production areas.
Corn is a focus of our agricultural system, receiving its share of research and development resources. Corn for silage is a benefactor of that focus, resulting in huge improvements in yields, feed quality and better production systems. Every fall, farms across the country will each harvest from a few hundred tons to thousands of tons of corn silage.
But corn silage is not all the same. It can range from a fibrous diet filler to a truly high-energy, "high-octane" feed.
At this time of year, factors such as variety selection and growing practice are already in place. But there are still many harvesting decisions and practices that can have a profound effect on the final feeding value of the crop.
The first is timing of the harvest. The objective is to find the right stage of maturity. You want to enable the accumulation of starch and balance it with the quality of the fiber. This maximizes the digestible fractions and minimizes the lignin, yet maintains sufficient moisture to permit fermentation.
I have used several parameters to judge the right time to let the choppers roll. The most common approach during the last few years has been to monitor the whole-plant moisture content. The guideline is 30% to 32%. At that moisture level, under most situations, the harvested silage is about right.
However, leaving the corn plant in the field a few more days and letting the moisture level drop a few extra points allows the plant to mature a little more. The result is that some additional starch is deposited in the grain, increasing the energy value of the silage.
Everything has its tradeoffs. In the case of corn silage, more grain and starch in the silage has to be balanced against the possibility of the plant becoming too dry for good fermentation and preservation. For large-acreage producers, it also decreases the window of time to get a large crop in the bunk. All of these concerns can be overcome with good planning and management.
Here’s the recipe for high-octane silage:
Target an extra three or four percentage points of dry matter for your silage harvest. This will vary depending on which part of the country you are in. It will also shorten your harvest window. You cannot let the harvest get beyond the point of adequate moisture to support good fermentation. A good harvest monitoring system needs to be in place so you will know the moisture of the silage coming into the bunk on a daily basis.
Dryer corn silage requires better chopping and processing. A 3⁄8" cut works well as long as everything is cut 3⁄8". Dull knives smash and grind, leaving a lot of smaller and larger particles in the mix.
Set the processer to process all the kernels and larger particles of silage. It is essential to have uniformly chopped and processed silage for good fermentation and feeding, especially with the dryer silages. Having the equipment well maintained and operated is also a must.
At the bunk, packing becomes more important. First, the dryer silage tends to be fluffier and resistant to packing. Second, you have to get a well compacted mass to exclude air and encourage rapid and proper fermentation. Make sure you have tractors with enough weight to do the job properly.
A good microbial system to support the fermentation is also important. With the reduced moisture, the natural fermentation process is slower to get started and more difficult to sustain. Using a reliable microbial system provides added insurance.
Finally, with dryer, more densely packed silages and marginally more difficult storage, bunk management becomes more important. The use of a silage defacer is a good practice. It keeps the face of the pile more dense and less subject to degradation by air penetration. Dryer silage is likely to have a shorter shelf life and lose some of the increased feeding values if not well managed.
Another system commonly used to increase the feeding value of corn silage is to chop the corn higher. Leaving an additional 12" or so of stalk in the field will decrease the overall moisture content and increase the grain-to-foliage content of the silage.
What is left in the field is some tonnage, but it is the most indigestible part of the plant. When buying grain to supplement diets, this is a practice that makes a lot of sense on many farms. When combined with chopping a little drier, it will make significantly higher-value silages.
The final step is to make sure your analytical and feed monitoring systems can measure and manage the increased value of your silage. Your ration programming system needs to be robust enough to take advantage of the higher-octane inputs in the diets.